This invention relates generally to a position detection system and computer methods for detecting physical objects within such position detection system. More specifically, it is related to a computer system that is implemented to detect physical objects within a physical game board or a physical toy for the purpose of interfacing with such computer system.
With the prevalence of home computers, an increasingly important goal within the game industry is to design a game system that incorporates the advantages of traditional board games and advantages of video or computer games. Such combined board game systems should generally be capable of detecting the presence of playing pieces or physical objects at different locations on the game board. Preferably, they should also identify other attributes, besides position, of the physical pieces.
Various type of computer games that interface with physical objects are described in British Patent Application Number PCT/US95/10096 filed by Superdimension Inc, published on Feb. 8, 1996 (Herein referred to as xe2x80x9cSuperdimension). For example, Superdimension refers to British Patent 2,103,943 as describing a sensing board and resonating pieces. The pieces include resonators that may be sensed by circuits in the board associated with particular position xe2x80x9ccells.xe2x80x9d The resonators are sensed by electromagnetic induction. Due to coupling between the coils in the playing pieces and the coils in the board, signals fed to the board stimulate the resonators and pick up a resonant signal that is produced by the resonators. Since different pieces have different resonators that are stimulated at different resonant frequencies, different pieces may be identified based on the frequency of the resonant signal that is picked up in a particular cell on the board.
The board incorporates two groups of circuits, each group having a circuit associated with each cell. One group of cells stimulates the resonators in any pieces on the cells by transmitting electromagnetic signals and the other group receives signals produced by the resonators in the cells in response to the stimulation. The coils in each group are interconnected and are individually addressable via a diode associated with each coil.
To determine the position of a particular piece on a cell, a pulse of electric current is supplied to the simulating coil of the cell, whereby a rapid change in current at the trailing end of the pulse results in oscillation of the resonator in the piece situated at the cell at its resonant frequency. The resonant oscillation induces a current signal in the sensing coil associated with the cell which signal is amplified and thresholded. For signals greater than the threshold, the oscillation frequency is measured to yield a corresponding digital signal. When a cell is empty, i.e. it does not accommodate a piece, there is no resonant xe2x80x9cringingxe2x80x9d and, therefore, the number of transitions is detectably low. In sum, this game system can only sense a position and a frequency dependent identity of the game piece.
Superdimension further describes other patents describing position sensing boards, some of which are capable of differentiating between different playing pieces, based on their individual resonating frequencies. Sensing of positional attributes of playing pieces and reacting accordingly is also performed in pinball machines, which sense the position of the pinball using a remote sensor. A ski-game, disclosed in patent SU 844011, uses photocells to detect whether ski-figure playing pieces are correctly located on a ski track and keeps score.
U.S. Pat. No. 5,169,516 discloses an interactive action toy system, in which two toy figures react to each other based on a sensed engagement position for both toys. SE 7812190, U.S. Pat. No. 4,341,385, GB 2237514, and U.S. Pat. No. 5,088,928 disclose computer games wherein a computer reacts to the position and/or previous position of a playing piece on a physical board by playing sounds and/or video graphics.
Although the above described game systems provide adequate game piece interaction for the user, these games only provide a limited number of ways to manipulate pieces, wherein the manipulation is detected by the position sensors. That is, these games only allow the user to select a type of piece and a position of the selected piece. For example, some sensing systems are incapable of detecting certain other object states, such as a z position of the game piece. Thus, the user may only move the piece within a two dimensional plane.
Additionally, since conventional game systems identify pieces based on their resonating frequency, the number of game pieces is necessarily limited by the number of resonating frequencies that are allowed by the particular sensing technology. For example, if a position sensing system only allows 64 different resonant frequencies, the game is limited to 64 types of pieces.
Thus, there is a need for an improved game system and a method for detecting a wide range of object states of physical objects within a position detection system. Additionally, there is a need to reduce the number of resonators that are required for detecting a large number of objects or a wide range of object states.
To achieve the foregoing and other objects and according to the purpose of the present invention, a method and apparatus for determining an object state of a physical object within a position detection system is disclosed. In general, the present invention provides mechanisms for converting the object state of the physical object into a corresponding resonator position state, wherein the object state differs from the resonator position state. The position state of the resonator may be detected and used to determine the object state of the physical object by translating the detected resonator state back into the associated object state. For example, a translation mechanism may be configured to convert a z position state of the physical object into an x position state of an associated resonator, and the x position state of the resonator may then be detected and used to determine the z position state of the physical object. Several other mechanisms for determining an object state from a different detected resonator state are further described below.
In one embodiment, a position detection system for determining a state of a physical object is disclosed. The position detection system includes a platform and a physical object positioned adjacent to the platform. The physical object has an object state that is changeable. The position detection system also includes a first resonator having a first resonator position state. The first resonator is arranged such that a change in the object state causes a change in the first resonator position state and such that the first resonator position state is different from the object state. The first resonator is further arranged to output a resonator signal that is associated with the first resonator position state when an excitation signal with a predetermined frequency range is received by the first resonator. The position detection system further includes a translation mechanism for translating the object state into the first resonator position state and a computer system arranged to output an excitation signal at the predetermined frequency range to the first resonator and receive the first resonator position state that is associated with the resonator signal that is output from the first resonator in response to the predetermined frequency range.
In one aspect of the invention, the platform is interchangeable and includes a second resonator having a second resonator position state, and the computer system is further arranged to receive the second resonator position state and determine a platform identity based on the second resonator position state. Additionally, the computer system may be further arranged to determine the object state by translating the first resonator position state into the object state.
A method of determining an object state of a physical object within a position detection system is also disclosed. The position detection system also includes a resonator having a resonator state that depends on the object state, and the resonator state is different from the resonator state. An excitation signal is sent with a frequency range to the resonator of the detection system. A position signal is received from the resonator. The position signal is based on the resonator state. The position state associated with the received position signal is translated into the object state.
These and other features and advantages of the present invention will be presented in more detail in the following specification of the invention and the accompanying figures which illustrate by way of example the principles of the invention.